Generation of THz emission from donor centers in silicon under intracenter optical pumping

Optical pumping of excited donor states in silicon crystals doped by antimony, phosphor, arsenic, and bismuth impurity centers by emission from a free electron laser yields stimulated terahertz emission (4-7 THz). The detailed study of silicon emission spectra provides information on intracenter phonon-assisted relaxation mechanisms in silicon at low lattice temperatures as well as on binding energies of excited states of donor centers.